Sterilization of liquids.



P. H. DAWE.

STERILIZATION OF LIQUIDS.

APPLICATION FILED APR.17, 1915.

Patented Feb. 27, 1917.

2 SHEETSSHEET I.

PHILIP HENRY DAWE, OF WESTMINSTER, LONDON, ENGLAND.

STERILIZATION 0F LIQUIDS.

Application filed April 17, 1915.

To all whom it may concern Be it known that I, PHILIP HENRY DAWE, a subject of the King of Great Britain. and Ireland, residing at Dacre House Victoria street, Westminster, London, S. W., Eng land, have invented certain new and useful Improvements in or Connected with the Sterlization of Liquids, of which the following is a specification.

This invention for improvements in or connected with the sterilization of liquids by electric current, alternating current being preferred, has for its object an improved method and apparatus therefor and consists in passing the liquid between two or more electrodes so arranged and supplied with electric current that the cross-sectional area of the efiective zone of current is small and a high and uniform current density obtained. The construction of the apparatus is such that a large useful area of electrodes is presented and the sparking distance between the electrodes increased. The electrodes are preferably supplied from the secondary windings of a static transformer in which case the primary current supply and therefore the secondary current supply are automatically controlled by a irheostat connected in the primary circuit. The rheostat comprises two sets of coupled plates arranged alternately in a vessel through which the liquid passes on its way to the electrodes so that the electrical resistance between the electrodes automatically increases on the Flow of the liquid decreasing or subsiding.

These principles and this apparatus may also be applied to electrical heating and to the chemical treatment of liquids where such chemical treatment is not for the purpose of sterilization.

A suitable current density for sterilizing milk is 40 amperes per square inch of sectional area of the electrical zone through which the milk passes at right angles, at a uniform rate of say one gallon per minute for every square inch of surface area of the zone. A. suitable voltage for one sixteenth square inch of sectional area and one fourth square inch surface area is 340 which consumes 800 watts and gives a current of 2?; amperes.

In the accompanying sheets of illustrative drawings,

Figures 1 and 2 show in sectional eleva-' Specification of Letters Patent.

Patented Feb. 27, 1917.

Serial No. 22,162.

Figs. 3 and 4 are similar views of a modi fied form wherein extra electrode surface is exposed.

Figs. 5 and 6 are sectional elevation and plan views respectively of an arrangement wherein central and annular electrodes are used.

Figs. 7 8, 9 and 10 give the straight modified forms of my invention.

Figs. 11 and 12 show diagrammatically the circuit arrangements wherein a static transformer automatically controlled by a rheostat is employed.

As seen in Figs. 1 and 2 the apparatus comprises a body a of insulating material into which a pair of narrow electrodes 71.12 are introduced, inlet and outlet pipes e and d being provided for the passage of the liquid. The electrodes present themselves to a comparatively small quantity of "liquid and a relatively high current density is thus obtained.

The arrangement shown in Figs. 3 and 4 is similar except that the electrodes 6 b are of channel shape and are set in recesses formed at the sides of the body a, thus presenting a: larger efl'ective area without increasing the cross-section of the electrical zone and at the same time increasing the sparking distance. Inthis and the above arrangement the passage for the liquid is square or rectan gular in order to insure a uniformity in the current density in the active zone.

'In'the form shown in Figs. 5 and 6 a circular body 6 is used with a central electrode 7 recessed into the top of a pedestal opposite an annular'electrode g recesse in the wall of the body 6.

In the form illustrated in Figs. 7 and 8 a rectangular passage for the liquid is formed in the body a but the electrodes 6 b are set in chambers a} a arranged at opposite sides of the central passage and communicating therewith by narrow openings a a The apparatus shown in Figs. 9 and 10 is similarly constructed but is circular and has one central electrode h and the other annular electrode '5 is shielded in a chamber j.

By this arrangement sparking between the electrodes is practically impossible, furthermore as the liquid supply subsides the electrical resistance between the electrodes is increased and so automatically reduces the current.

When the apparatus is to be supplied with current from a static transformer the arrangement shown in Fig. 11 is preferably employed. The primary circuit k of the transformer is connected in series with a rheostat comprising a tank Z of insulating material and two sets of coupled plates m at between which the liquid passes on its ,way to the electrodes.

When it is found to be impractical to arrange the apparatus as illustrated in Fig. 11 the arrangement shown in Fig. 12 may be employed wherein two static transformers are used. As seen the primary winding 0 of one transformer is connected to the supply leads and the secondary winding p to the liquid rheostat and the primary winding 9 of the second transformer. The secondary 9 of this transformer is then connected to the electrodes 12 22 When using this apparatus for sterilizing liquids, milk for example, the liquid is caused to pass through the apparatus at such a rate that it is only perceptibly heated.

What I claim and desire to secure by Letters Patent is 1. A liquid sterilizer, including a tube, an annular shoulder, formed around the inner face of the tube, an annular electrodepositioned on said shoulder, and around the inner face of the tube, and a pedestal, positioned within the tube, said pedestal being in spaced relation to the walls of the tube, and carrying a second electrode.

2. A liquid sterilizer including a tube, an annular shoulder, formed around the inner face of the tube, an annular electrode, positioned on said shoulder and around the inner face of the tube, a pedestal, positioned within the tube and being in spaced relation to the walls thereof, carrying a second electrode upon its upper end, the liquid being adapted to flow between the pedestal and the walls of the tube.

In testimony whereof 1 affix my signature, in presence of two witnesses.

v PHILIP .HENRY DAWE.

Witnesses:

A. WASH, J r., C. O. 'HOLDER. 

